Fragments

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Feb 042014
 

Once there was a box. Inside the box was a board, and inside the board was a chip. Inside the chip was a carrier, and on that carrier was a die. And when the die came off the carrier it broke, and the pieces looked like this:

2014-02-03-214452

More pretty pictures below.

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 Posted by at 10:38 am
Feb 022014
 

Firefox on a Mac SEMac SE video driver

It is a truth, universally acknowledged, that an engineer in possession of an antique computer must be in want of hacking it. Last year I reverse engineered the Easter Egg photographs from a Mac SE that I found on the side of the road and that machine has been sitting idle since then, so I took inspiration from NYCR founder Dave Clausen’s six year old 24th anniversary Mac project and turned my old SE into a “30th anniversary Macintosh” with a new ARM motherboard running Linux. Unlike Dave, I was able to interface with the original 9″ CRT thanks to the programmable hardware in the Beaglebone Black.

Mac SE video pulses
The CRT was still in good shape and the m68k motherboard would startup (although we have no media or OS for it) so it was fairly easy to reverse engineer the pinout and waveforms for the combination power-supply and video connector. The all-in-one Macs shared a common power-supply for the monitor, analog board, motherboard and drives, so the same cable carries video, hsync, vsync, +5, -5, +12 and -12 Volts.

Mac SE video driver
With these timing measurements I was able to write a software video card that runs inside the BeagleBone Black’s PRU to display a user-space framebuffer, and then used Xvfb to render X11 into a shared memory buffer that could be exported to the PRU’s memory. Working with a bare CRT like this can be scary — the monitor is not even remotely multisync and vsync a few percent off from its desired 60.1 Hz refresh rate generates very bad buzzing sounds.

You can enjoy the dithered 1-bit cat videos above and relive the era with monochrome visuals for xeyes and other classic applications. If you want to build your own and see the specifics of the design, there are more details on my website, trmm.net/Mac-SE_video.

Mac SE with a BeagleBone Black motherboard
UPDATE 2014-02-09: Original ADB Keyboard and mouse support is now working. adb2usb source code for a Teensy 2.0.

Jan 242014
 

If you’ve ever been running at night in New York City, you know that it can be dangerous, especially if other people can’t see you. This jacket was my attempt to not get flattened by a bicycle at night. Of course, I could have just bought some plain running lights, but what fun is that? Not only does this jacket have seven awesome flashy modes, but each mode responds to my heart rate!

 led_image_2 01

Since my Garmin heart rate monitor uses the ANT protocol, I could easily intercept the heart rate information for my jacket. I used a Teensy and an ANT transceiver to control two LED strips based on the current mode selection and the current heart rate. The jacket is powered by rechargeable battery packs.

My first run with the jacket was the 2013 New Year’s Eve midnight run in Central Park. Since then, I’ve worn it to a few races and even to a tech talk. The full build out details can be found here.

 

Jan 072014
 

DSC_2963

This weekend at NYC Resistor we are teaching a class on the BlinkyTape. If you’ve been wanting to make a project that incorporates LEDs and custom lighting, then this might just be the class for you!  BlinkyTape is one of the easiest ways to make interactive lighting installations, so this is a great class for makers of every level.

Bring your laptop and we’ll teach you how to create your own animations and patterns using your BlinkyTape. A BlinkyTape, usb cable, and power supply will be included in the class fee.  Which is amazing!

There are a few seats left so sign up now for this exclusive executive tour of this luxury LED lighting solution!

OMG first post for 2014!

 

 

Dec 272013
 

Porter

NYC Resistor has been known to occasionally homebrew a beer or two. We have members interested in the topic, and friends in the wider brewing community of NYC. However, since I’ve returned from California, I’ve found myself more and more interested in beer brewing at Resistor. Luckily Travis, a fellow member is also deeply into the homebrew hobby. Together we’ve been spinning up a few different projects over here. There will be some great follow up posts on those other projects I am sure. Read on for more about brewing at NYC Resistor!

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Dec 092013
 

Bring your cash and your curiosity to our FIRST EVER HOLIDAY CRAFT FAIR December 15, from 12-6pm. We’ll offer a free soldering workshop that day as well as host a number of makers in our area who’ll be selling their items. Also for our first 100 visitors, a free NYC Resistor holiday ornament!

Anyone from the community also interested in selling at the event is welcome to email us for an open spot while they last at resistorholiday@gmail.com.

 Posted by at 12:48 pm
Dec 082013
 

Adafruit FLORA and Neopixel ring

Next weekend at NYC Resistor we are teaching a class on the Adafruit FLORA and Neopixel. These round Arduino compatible controller boards are a great base for wearable projects like watches, jackets and neck ties, as well as holiday decorations. Bring your laptop and we’ll teach you to make the LED ring blink with patterns of your own design. No prior programming required. The class fee includes a FLORA board, batteries, cabling, 4 RGB LED pixels and a 16 RGB LED ring.

Nov 252013
 


In a show of solidarity with our oppressed Meleagris gallopavo brethren, there will be no craft night this Thursday, November 28th. We recommend gathering together with friends and loved ones and sharing a hearty seasonal meal of kale and pine nuts instead. See you all next week!

Nov 182013
 

AVR RFID with extra capacitor

Last year we wrote about building HID Proxcard RFID tags with attiny85 microcontrollers (based on Micah’s avrfid.s code). The C version only supported classic 26-bit cards, but I recently needed to support the “secure” HID Corporate 1000 35-bit format.

Based on Daniel Smith’s writeup on the format and some digging around, I figured out that the MFG_CODE for this format is 10-bits long with the value 0x005. He also pointed out that the 26-bit firmware had the wrong code — it is not the 20-bit code 0x01002, but is instead the 19-bit code 0x0801 and the bottom bit is part of the parity computation for the card id. If you’re using a HID branded Proxcard reader, the value that it outputs is the entire data portion, including all of the parity bits, but does not include the MFC_CODE part. If anyone knows of a table of these codes, please let me know!

I’ve updated my firmware with these changes and it works great. Emulating a 35-bit card takes 846 bytes of flash (nine more than the 26-bit cards since the state machine stores one bit per byte), so it might be possible to port this to the attiny10. I’ve also found that the tags work much better with a small capacitor across the two clock pins, as shown in the above photo.